Method of identifying cellulose



3,059,980 Patented Get. 23, 1962 Free 3,059,989 IVIETHOD F IDENTIFYENG CELLULOSE ACETATE BY FUGKTTVELY TINTING Carroll Fred Chandler, Waynesboro, Va., assignor to E. I.

du Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware No Drawing. Filed May 26, 1959, Ser. No. 815,807

Claims. (Cl. 856) This invention relates to the fugitive tinting of yarns of cellulose organic acid esters such as cellulose acetate.

It is a common practice in the textile industry to apply fugitive tints to yarns in Order to assist identification during processing. It is often a great advantage to be able to identify particular ends in a warp during weaving or to distinguish at a glance one kind of yarn from another. Again, in preparing mixtures of two diflferent kinds of staple fiber, for example a mixture of cellulose acetate staple fiber, and Wool fibers, it is convenient to tint one of the fibers so that a visual examination of the mixture enables one to tell whether the blending of the fibers is complete or adequate. It is, of course, essential that the fugitive tint applied should be readily removable, preferably by a normal scouring operation, when it has served its purpose. For this to be possible, the tint must be such as to resist fixation on the textile fibers even after the tinted material has undergone sizing, steaming, conditioning with respect to moisture content, or heat setting treatments such as are commonly applied to fabrics containing cellulose triacetate or other synthetic fibers.

Economy and ease of application indicate that fugitive colors are best applied with finish emulsion at the spinning machine. However, the choice of the acid colors suitable for this purpose is extremely limited. As-spun secondary cellulose acetate yarns produced by dry spinning from acetone have a high solvent content. The usual acid colors will soak into the filaments and become non-fugitive due to the high solvent and water content of the packages. Actually with 900 and heavier deniers, no acid colors have heretofore been found which are fugitive at the depth of shade required for commercial use. With the limitations on dye selection especially for the production of the heavy denier tinted yarn, additional colors demanded :by the trade could only be supplied by a costly and objectionable winder tinting process. This comprises the application of the tinting agent from an aqueous medium during a re-winding operation. The winder tinting process suffers from several disadvantages. Color application is of necessity random and of varying depth from the inside to the outside of the packages. Water content must be controlled to insure fugitivity and even at minimum water content, soft packages will often develop after aging. In general the operation is messy and poses serious housekeeping problems.

It is an object of this invention to provide a tinting process which is eminently suited for the fugitive tinting of filament yarns and threads of organic acid esters of cellulose, such as cellulose acetate. Another object is to provide a process of fugitive tinting freshly spun cellulose acetate yarns containing from 1025% of acetone. Another object is to provide a greater variety of fugitively tinted cellulose acetate yarns. A further object is the tinting of yarns having a denier of 900 and greater as spun, with a solvent content of 10-25% acetone to produce a tinted filament which can be easily scoured to remove the tint. Other objects will become apparent from the following description.

These objects are realized by the invention which comprises applying as a fugitive tinting agent, an aqueous solution of a fully-chromed monoazo dye containing at least one alkali metal or ammonium sulfonate group per dye molecule, said dyestuff being insoluble in ethyl acetate.

By full-chromed monoazo dyes or similar terminology used in the present specification, is meant dyes containing one azo group and one chromium ion per molecule of dye. Representative dyes are presented in Table I below with references to suitable structure identification in the Color Index, second edition, volume 3. It may be further noted from the indicated structures that each representative dye contains at least one sulfonate salt group, and that a least one nitrogen atom from the azo group is attached to an aromatic ring. Preferably this aromatic ring bears a hydroxyl group in a position ortho to the nitrogen atom.

The full-chromed monoazo dyes are preferably applied at the spinning machine to freshly formed cellulose acetate yarn to the extent of from about 0.01% to about 0.06% by weight based on the air dry weight of the yarn. The yarn may be simultaneously tinted and finished by dissolving the dyestufi in a suitable aqueous finish emulsion containing the usual textile finishing agents such as olive oil, sulfonated olive oil, soap, polyhydric alcohol, mineral oil, etc., and applying the composition to the yarn as it leaves the spinning cell by a conventional yarn contacting roll applicator dipping in a trough. The tint may, however, be applied quite independently of the finish by contacting the yarn with a dilute aqueous solution of the same in any suitable manner.

The dye content of the finish emulsion is not critical. Ordinarily it will contain from about 0.20% to about 0.5% of dye. Where the yarn is dyed independently of the finish the same percentage may be used in aqueous solutions.

Even though the yarn to which the dye is applied may, and usually does, contain a very high concentration of solvent, up to 0.06% of dye (based on the air dry weight of the yarn) may be applied to freshly spun cellulose acetate yarn before its initial windup without resorting to any special procedures. Since the tinted yarns have an unusually high degree of fugitivity, the dyes employed in the process of the invention are outstanding for the fugitive tinting of cellulose acetate yarn. Although as much as 0.06% of the dye may be applied to the yarn, in general, for fugitively tinting yarn to be used in the manufacture of woven goods, substantially less than this amount can be used to provide adequate tinting. Dye applications of from about 0.015% to 0.03% by weight are preferred.

The invention is further illustrated by the following example where percentages are by weight.

EXAMPLE I An aqueous tint finish solution is prepared of the following composition:

Percent Sulfonated olive oil 5 Mineral oil 14.5 Triethanolamine olea-te 5.5 Chromacyl Blue GG 0.23 Water 74.77

at the rate of about 175 yards per minute. denier was about 900.

A mixed fabric was made comprising the cellulose acetate yarn so treated and viscose rayon yarn. The coloring matter in the cellulose acetate yarn was easily discharged by treating the fabric for ten minutes in 70 C. aqueous soap solution containing 0.2% sodium oleate. Upon examination of the fabric, it was noted that the cellulose acetate yarn had completely discharged its color and that no staining of the viscose rayon yarn had occurred. Furthermore, the short time and low temperature discharge treatment had not materially affected the luster of the cellulose acetate yarn.

In similar tests, other dyes were used in place of the Chromacyl Blue GG and similar results were obtained. The dyes tested are listed in Table I below.

The yarn Table I Trade Name: Color Index No. Chromacyl Blue GG-acid blue 158 14,880 Chromacyl Pink BN-acid red 186 18,810 Chromacyl Yellow Nacid yellow 54 19,010 Chromacyl Black W-acid black 52 15,711 Chromacyl Blue R--acid blue 161 15,706

Chromacyl Yellow GRacid yellow 99"-- 13,900 Chromacyl Orange GR Chromacyl Pink 3B The dye Chromacyl Blue G6 is a full-chromed monoazo dye of the formula HO SOsNa Chromacyl Pink BN is a full-chromed monoazo dye of the formula S OsNB OH HO (fi-III NaO aS- N=NO N and Chromacyl Yellow N is a full-chromed monoazo dye of the formula Parts No. 50 mineral oil 58 Ucon LB-385 3 Flexricin 62 -s 14.4 Brown peanut oil 2 Atlas 6-1052 3 Triethanolamine 7 Coconut fatty acid 12.6

Twenty-two and four-tenths pounds of the base are dispersed in 76 pounds of water containing 1.5 pounds of Zelec NO, 0.5 pound of Chromacyl color and 0.1 pound of Dowicide A.

Dull cellulose acetate yarn in a bundle having a total denier of and comprising 40 filaments was dry spun from an acetone solution. The yarn contained about 0.4% titanium dioxide and about 20% solvent. It was then passed over a rotating finish applicator roll, dipping into a finish trough containing the emulsion. The finish content of the yarns produced was 2.7%. Chro macyl Pink BN, Orange, GR, Yellow N, and Blue GG were each applied in the abovedescribed manner. After four weeks of aging it was found that the Chromacyl colors were all fugitive.

Closely related dyes of other series were tested and found unsuitable. For example, several members of the Capracyl series were used.

None of the Capracyl colors were fugitive under these conditions. Spinning tests similar to those made above were performed using Capracyl Orange R, Red BB, and Blue G. None of the yarns so treated discharged their color upon scouring. The Capracyl dyes are half-chromed monoazo dyes containing one chromium atom associated with two molecules of azo compound. They do not contain free sulfonic acid groups. The Color Index references for Capracyl colors are:

Capracyl Orange R (CI Acid Orange 60) Capracyl Red BB (CI Acid Red 178) Capracyl Blue G (CI Acid Blue They appear in volume I of the Colour Index, pages 1079, 1167, and 1301, respectively.

It is unexpected that the full-chromed monoazo dyes used in the present invention, commonly considered as dyes suitable for use on proteinaceous material such as wool, silk, leather, and polyamides, should fugitively tint cellulose acetate. It is even more unusual that fugitivity is obtained even when these dyes are applied under conditions normally considered as destroying fugitivity of the dyed structure. These properties permit high spinning speeds without sacrificing any degree of fugitivity, since the resulting high solvent content yarns do not fix these dyes.

It is understood, of course, that the invention is not restricted to the exact conditions set out above for purposes of illustration but comprehends all equivalents and modifications included in the spirit and terms of the following claims.

What is claimed is:

1. A method for assisting in the identification of a cellulose acetate yarn during processing comprising fugitively tinting such yarn with up to 0.06% based on the air-dry weight of the yarn of a full chromed monoazo dye containing at least one sulfonate salt group per dye molecule and having at least one nitrogen atom from the azo group attached to an aromatic ring, and thereafter scouring the yarn thereby removing the dye after it has served its identification purposes.

2. The process of claim 1 wherein the amount of dye applied is between about 0.015 and 0.03% based on the air-dry weight of the yarn.

3. The process of claim 1 wherein the scouring is by means of an aqueous soap solution.

4. The process of claim 1 wherein the dye used is a full chromed monoazo dye of the formula HO SOaNa 5. The process of claim 1 wherein the dye used is a full chromed monoazo dye of the formula SO3Na 7. The method of claim 1 wherein the cellulosic yarn contains at least of acetone.

8. The method of claim 7 wherein the liquid dye containing composition is a finish emulsion.

9. The method of claim 7 wherein the yarn denier is at least 900.

10. A method for assisting in the identification of a cellulose acetate yarn during processing comprising fugitively tinting such yarn with up to about 0.06% of full chromed monoazo dye of the formula OH HO S0 Na Na 03S- scouring the yarn for ten minutes at C. in an aqueous soap solution containing 0.2% sodium oleate thereby removing the dye after it has served its. identification purposes.

References Cited in the tile of this patent UNITED STATES PATENTS 1,693,759 L-ardy Dec. 4, 1928 1,852,137 Whitehead Apr. 5, 1932 1,946,951 Straub Feb. 13, 1934 1,979,913 Straub Nov. 6, 1934 2,492,394 Olpin Dec. 27, 1949 2,802,714 Olpin Aug. 13, 1957 OTHER REFERENCES British Rayon and Silk Journal, April 1953, p. 54, esp. paragraph beginning at bottom of left column.

Journal of the Textile Institute (J.T.I.), Proceedings, August 1954, Meitner et al., Fugitive Tinting, pp. P369 P379, esp. at P372, fourth sentence of second complete paragraph.

Venkataraman: Synthetic Dyes, Academic Press, New York, 1952, vol. 1, p. 284, esp. discussion under 

1. A METHOD FOR ASSISTING IN THE IDENTIFICATION OF A CELLULOSE ACETATE YARN DURING PROCESSING COMPRISING FUGITIVELY TINTING SUCH YARN WITH UP TO 0.06% BASED ON THE AIR-DRY WEIGHT OF THE YARN OF A FULL CHROMED MONOAZO DYE CONTAINING AT LEAST ONE SULFONATE SALT GROUP PER DYE MOLECULE AND HAVING AT LEAST ONE NITROGEN ATOM FROM THE AZO GROUP ATTACHED TO AN AROMATIC RING, AND THEREAFTER SCOURING THE YARN THEREBY REMOVING THE DYE AFTER IT HAS SERVED ITS INDENTIFICATION PURPOSES. 